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Neurogenesis - Anatomy & Physiology (view source)
Revision as of 16:36, 26 August 2008
, 16:36, 26 August 2008→Organisation of the Nervous System
===Somatic Nervous System===
===Somatic Nervous System===
*Sensory neurones enter the CNS through a '''dorsal root'''.
*Sensory neurones enter the central nervous system (CNS) through the '''dorsal root'''.
**Sensory neurones have their cell bodies in dorsal root ganglia (DRG). DRG are evenly spaced along the spinal cord.
**Sensory neurones have their cell bodies in dorsal root ganglia (DRG). DRG are evenly spaced along the spinal cord.
*Response to the stimulus is mediated by a single motor neurone.
*Response to the stimulus is mediated by a single motor neurone.
**Somatic motor neurones have their cell bodies in the CNS. They leave the CNS by the '''ventral root'''.
**Somatic motor neurones have their cell bodies in the CNS. They leave the CNS by the '''ventral root'''.
*Dorsal and ventral roots converge to form '''spinal nerves'''.
*Dorsal and ventral roots converge to form '''spinal nerves'''.
===Autonomic Nervous System===
*Sensory neurones also enter the CNS through the dorsal root, with their nuclei in DRG.
*In contrast to the somatic nervous system, the motor component is in two parts; a preganglionic and postganglionic neurone.
**The preganglionic neurone has it's cell body in the CNS. It exits via the ventral root and synapses with the postganglionic neurone.
**Cell bodies of the postganglionic neurone lie outside the CNS in ganglia.
***Ganglia of the ''sympathetic'' nervous system are near the '''spinal cord'''.
***Ganglia of the ''parasympathetic'' nervous system are near the '''target organ'''.